Art of telegraphy.



UNITED STATES- Patented May 26, 1903.

PATENT OFFICE.

HENRY A. ROWLAND, OF BALTIMORE, MARYLAND, ASSIGNOR TO THE ROWLAND TELEGRAPI-IIO COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF NEW JERSEY.

'ART OF TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 729,420, dated May 26, 1903.

Application filed December 2, 1899. Serial No. 739,011. (No model.)

To aZZ whom it may concern:

Be it known that I, HENRY A. ROWLAND, a citizen of the United States, residing at Balti more city, in the State of Maryland, have invented certain new and useful Improvements in the Art of Telcgraphy; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in methods of transmitting intelligence over an alternating-current circuit or any electric circuit having capacity and upon which there is impressed an electromotive force of a poriodically-varying character and in which there is a natural difference in phase between the impressed electromotive force and resultant current.

The said invention consists, substantially, in adjusting the electrical properties of a circuit of the above character at or in the region of the point of transmission until the impressed electromotive force and resultant cur rent are at that point brought into phase, selecting determinate semicycles of the current, and suppressing these by beginning at a point in the circuit where the current and electromotive force are both zero, the number and order of the semicycles thus suppressed representing the signal or the character of the code employed.

The rapid interruption or breaking of the circuit consequent upon the transmission of signals in the manner above stated,"bn't with out the phase adjustment, wouldordinarily, give rise to great sparking at the transmitter and a consequent lack of uniformity or accuracy at the receiver. This fault may, however, be diminished to a great. extent by ad-. justing the transmitting apparatus so that the times of circuit interruption will coincide with the times of zero-current, as the point of least sparking has been found to be at or very nearsuch times of current propagation; but where there is a difierence of phase between the impressed electromotive force and resultant current an alternating-cllrrent circuit cannot be broken without at least some sparking. If, however, the impressed electromotive force and current are brought into phase at the point where it is desired to interrupt the circuit and this interruption is timed to commence at the point of zero-current,and electromotive force,-. the sparking will entirely disappear. This adjustment of the phases is accomplished, according to the present'invention, by inserting in the circuit in the region of the point where it is desired to interrupt the current one or more self-induction coils, which are adjusted relative to the frequency of the alternations and distributed capacity of the line until the self-induction and capacity at that point neutralize each other, when the angle of phase between the impressed electromotive force and resultant current at that point will become zero.

The said invention will be described in greater detail with reference to the accompanying drawings, in which I have shown a form of apparatus by. which the method embodying thesaid invention may be carried out. Referring to the accompanying drawings, Figure 1 represents in diagram the principle of my invention. Fig. 2represents the same, but in which the position of the self-induction coil at the beginning of the line is changed. Fig. 3 represents a case in which the telegraph-line wire is supplanted by a cable. Fig. 4 represents a plan view of a portion of the transmitting-tape, and Fig. 5 represents a similar View of the record-tape.

Similar letters refer to similar parts throughout the several views. A represents an alternating-current generator or any other source of electrical supply which will deliver to the line a succession of wave impulses. V

H represents the line, having a capacity represented by thecondensers L L and connected to one pole of the generator, while the other pole is connected to earth, 'as shown though the whole circuit may be metallic, if desired.

At a point Where it is desired to impress the intelligence upon the circuit I locate a transmitter of such a character that it will suppress determinate semicycles of the line-'' current for each character or signal transmitted, a form of such transmitter comprising the pointed brush or stylus O, the adjustable contact-block D, and transmittingtape M, the said block being connected to the line by the wire F. The tape M is provided with a series of perforations m, which are adapted to pass over the block D and in the path of the brush 0, and are of such a size, so spaced, and driven at such a speed that the brush C meeting the contact-piece D through the perforations will transmit to line successive impulses or semicycles of the current, the small spaces between adjacent perforations occurring at or about the points of zero-current. The tape may be driven at the proper speed for accomplishing this in any convenient manner, though the means that I have shown for doing this consists in providing the tape with a series of perforations m, which are adapted to engage the toothed wheel driven by the alternator. As long, therefore, as an unbroken series of perforations m pass'beneath the brush 0 at the proper speed an uninterrupted series of impulses will pass over the line. Therefore if the perforations are of sucha size as to allow one complete semicycle to pass to line as long as the brush 0 makes contact through it with the block B the omission of this perforation would suppress one complete'semicycle. If two perforations are omitted, two semicycles will be suppressed, and so on, so that by arranging the perforations upon the tape M in any desired order the semicycles will be suppressed or transmitted in the same order. Messages may be transmitted in this way, for example, by allowing the suppression of one impulse to represent a dot and the suppression of two impulses to represent a dash or by allowing any selected number of complete impulses or semicycles to represent a dot or dash or other sign or symbol of any desired code or system. This transmitter, however, is only one form of device for suppressing the impulses in the manner indicated. This may be done also by locating in the main line a magnetic circuit-breaker operated by a suitable current-selecting device, or it may be done by the transmitting means shown and described in the Patent'No. 622,636, granted to me on April 4, 1898, or, in fact,any device which will suppress the semicycles according to the code or system selected may be used. So long as there is a diflerence of phase between the impressed electromotive force and resultant current at the point of transmission there will be sparking at the point of the brush 0, notwithstanding that the apparatus is so adjusted as to cause the suppression of the,

semicycle to commence at the point of zerocurrent, and this sparking is harmful not only on account of the fact that it consumes and injuries the end of the brush, but because the suppression will be ragged, and hence any receiver depending upon the clearness of the relation between the suppressed and unsuppressed semicycles will be very in uch afiected. This sparking is practically eliminated by bringing the impressed electromotive force and resultant current into phase at the point where the suppression is eifected. I do this by adjusting the electrical properties of the line at that point until the capacity and selfinduction neutralize each other, and for this purpose I insert in the line the self-induction G, with the proper'resistance, the said induction being preferably adjustable by means of the sliding core 9. This coil may be connected either between the generator and transmitter, as shown in Fig. 1, or on the other side of the transmitter from the gen erator, as shown in Fig. 2, or in both places.

Theoperation of bringing the electromotive force and current into phase at the transmitter and determining when the phaseangle is zero is quite simple, one way of accomplishing itrbeing to connect in the line an alternating-current volt-meter and ammeter and a direct-reading alternating-cu rrent wattmeter, which will give the true watts. Then the self-induction G is adjusted until the apparent watts or product of the volts and amperes indicated by the volt-meter and amineter are equal to.the true watt-s or the quantity indicated by the direct-reading wattme- 'ter, as cos 3 V C \V and W cos 9) W Therefore 0 when V U itual volts, '0 virtual current, W actual watts,

and V) the angle of phase difference. The angle of phase at the transmitter having been adjusted to zero, the tape with the message upon it is then placed in position and adjusted so that the spaces between the successive uninterrupted perforations willoccurexactly at points of zero-current and electromotive force, when the tape is then fed through the transmitter and the impulses or semicycles modified as described. Being thus transmitted, the messages may be received in any desired way. In the drawings Ihave shown a chemical-receiver K, which makes such a record as that shown in Fig. 5, where the successive marks h each represent an unsuppressed impulse or semicycle and the spaces k and k suppressed semicycles, the space la indicating that one semicycle has been suppressed and that two have been suppressed. A similar record may be produced by a Morse register or the semicycles may be suppressed in groups, as described in my Patent No. 622,636,bef0re referred to, and recorded upon a printer, or, in fact, any means of recording the semicycles modified as described may be employed.

Fig. 3 simply shows an application of my ICO IIO

invention to a cable-line H, in which case the capacity would be much larger than that of a land-line. In the event that there is a transmitter at each end of the line there would also be the added inductance at each end of the lineas, for example, in the case of a duplex line or a simplex line in which signaling is done in both directions.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

1. The improvement in the art of telegraphy which consistsin impressing an alternating electromotive force upon a line, adjusting the difierence of phase between the impressed electromotive force and the resultant current to zero at or near the point of transmission, and modifying a predetermined number of the semicycles of current to represent each character transmitted, substantially as described.

2. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the difierence of phase between the impressed electromotive force and the resultant current to zero at or near the point of transmission, and suppressing a predetermined number of the semicycles of current to represent each character transmitted, substantially as described.

3. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the ditference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, modifying a predetermined number of the semicycles of said current and recording the same, substantially as described.

4. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon aline, adjusting the difference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, modifying the semicycles of the said current according to a code and recording the semicycles so modified, substantially as described.

5. The improvement in the art of, telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the difference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, modifying the semicycles of the said current according to a code and recording the semicycles both modified and unmodified, substantially as described.

(5. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the ditference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, suppressing the semicycles of the said current according to a code and recording the semicycles so suppressed, substantially as described.

7. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the difference of phase between the impressed electromotive force and resultant current to zero, at or near the point of transmission, suppressing the semicycles of the said current according to a code and recording the semicycles both suppressed and unsuppressed, substantially as described.

8. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, and adjusting the difierence of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission by inserting a self-induction in said line properly adjusted, substantially as described.

9. Theimprovement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, and adjusting the difference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission by causing the self-induction and capacity of said line to neutralize each other at or near the point of transmission, substantially as described.

10. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, and adjusting the difference of phase between the impressed electromotive force and the resultant current to zero at or near the point of transmission by adjusting the self-induction of the line relative to the capacity until the two neutralize each other at or near the point of transmission, substantially as described.

11. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, inserting in the line a variable self-induction and adjusting the difference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission by adjusting the said self-induction relative to the capacity, substantially as described.

12. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting thedifference of phase between the impressed electromotive force and resultant current to zero at ornear the point of transmission, tra nsmitting individual semicycles of the current and recording the same, substantially as described.

13. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the difference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, beginning at the point of zero-current and sup- ICO pressinga predetermined number of the semicycles of said on rren t for each character transmitted and recording the semicycles both suppressed and unsuppressed, substantially described.

14. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the difference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, beginning at the point of zero-current and suppressinga predetermined number of the semicycles of said current for each character transmitted and recording the semicycles thus suppressed, substantially as described.

15. The improvement in theartof telegraphy which consists in impressing upon a line an alternating electromotive force, adjusting the difference of phase between the impressed electromotive force and the resultant current to zero at or near the point of transmission, and modifying the semicycles of the current in groups, each group representing one or more characters, substantially as described.

16. The improvement in the art of telegraphy which consists in impressing upon a line an alternating electromotive force, adjusting the difference of phase between the im pressed electromotive force and the resultant current to zero at or near the point of transmission, and suppressing the semicycles of the current in groups, each group representing one or more characters, substantially as described.

1'7. The improvement in the art of telegraphy which consists in impressing upon a line an alternating electromotive force, adjusting the difference of phase between the impressed electromotive force and the resultant curreht to zero at or near the point of transmission, and suppressing the semicycles of the current in groups, each group representing one or more characters, and recording the messages so transmitted, substantially as described.

18. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the difference of phase between theimpressed electromotive force and resultant current to zero at or near-the point of transmission, suppressing a plurality of the semicycles of the current to represent a character, and making a Visual record of each semicycle, substantially as described.

19. The improvement in the art of telegraphy which consists in impressing an alternating electromotive force upon a line, adjusting the difference of phase between the impressed electromotive force and resultant cu rrent to zero at or near the point of transmission, suppressing a plurality of the semicycles of the current to represent the characters thus transmitted, and makinga visual record of each semicyle, substantially as described.

20. The method of transmitting intelligence, over a circuit upon which there is impressed an electromotive force rising and falling in value, which consists in reducing the difference of phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, and modifying wave impulses at that point to represent the signal transmitted, substantially as described.

21. The method of transmitting intelligence over a circuit upon which there is impressed an electromotive force rising and falling in value, which consists in adjusting the properties of said circuit at or near the point of transmission until the difference of phase between the impressed electromotive force and resultant current atthat point is reduced to zero, said adjustment being effected by the neutralization of the capacity by the self-induction at that point, and modifying wave impulses to represent the signal transmitted, substantially as described.

22. The improvement in the art of telegraphy, which consists in impressing an alternating electromotive force of sine-wave or approximately sine-wave form upon a line, adjusting the difference in phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, and modifyinga predetermined number of the said semicycles for each character transmitted substantially as described.

23. The improvement in the art of telegraphy, which consists in impressing an alternating electromotive force of sine-wave or approximately sine-wave form upon a line, adjusting the difference in phase between the impressed electromotive force and resultant current to zero at or near the point of transmission, beginning at the point of zero-current and suppressinga desired number of the semicycles in any desired order for each signal, and recording the transmitted with reference to the suppressed semicycles, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

HENRY A.RO LAND.

Witnesses:

MURRAY HANSON, WILLIAM H. BERRY.

IIO 

